asita no kaigi no siryou wo kousikisaito kara daunroodosite okimasu.

Each の links nouns together.

• 明日の会議 = tomorrow's meeting / the meeting tomorrow
• 明日の会議の資料 = the materials for tomorrow's meeting

So the phrase builds step by step:

1. 明日 → tomorrow
2. 明日の会議 → tomorrow's meeting
3. 明日の会議の資料 → the materials for tomorrow's meeting

In English, we often use of, for, or an apostrophe 's. In Japanese, の covers a lot of those relationships.

A natural way to group it is:

• 明日の会議 = the meeting tomorrow
• 明日の会議の資料 = the materials/documents for that meeting

So 資料 is the main noun, and everything before it describes what kind of materials they are.

You can think of it as:

• [tomorrow's meeting] + materials

This kind of noun stacking is very common in Japanese.

を marks the direct object of the verb.

Here, the verb is ダウンロードしておきます, and the thing being downloaded is 資料.

So:

• 資料をダウンロードしておきます = I will download the materials in advance

A simple way to spot を is to ask: What is being downloaded?
Answer: 資料

から means from and shows the source.

• 公式サイトから = from the official website

So the sentence says the materials will be downloaded from the official website.

This is the same から you see in many source/origin uses:

• 学校から帰ります = I return from school
• 友だちからメールをもらいました = I got an email from a friend

This is one of the most important parts of the sentence.

〜ておく often means:

• do something in advance
• do something in preparation
• do something and leave it that way

In this sentence, the main meaning is do in advance.

So:

• ダウンロードします = I will download it
• ダウンロードしておきます = I will download it beforehand / in preparation

Because the sentence starts with 明日, the nuance is:

• I'll download the materials ahead of tomorrow's meeting.

Not always, but that is one very common use.

The two big uses are:

1. Preparation

   • 明日のために準備しておく = prepare for tomorrow in advance

2. Leave something as it is

   • ドアを開けておく = leave the door open

In your sentence, it is clearly the first meaning: downloading the materials in advance for the meeting.

ダウンロードする is a suru-verb.

That means it behaves like this:

• dictionary form: ダウンロードする
• polite form: ダウンロードします
• て-form: ダウンロードして

Then おきます is added:

• ダウンロードしておきます

You may sometimes see ダウンロードをする, but ダウンロードする is more standard and natural in many cases.

Japanese sentences normally place the main verb at the end.

So this sentence is built like:

• 明日の会議の資料を = the materials for tomorrow's meeting
• 公式サイトから = from the official website
• ダウンロードしておきます = will download in advance

This verb-final structure is very normal in Japanese.

Japanese non-past forms cover both present and future.

So おきます can mean:

• do / will do

Because the sentence includes 明日, the time is clearly future:

• 明日 = tomorrow
• therefore ダウンロードしておきます = will download in advance

Japanese usually does not need a special future tense form the way English does.

Japanese often leaves out the subject when it is understood from context.

So this sentence could mean:

• I will download...
• We will download...
• sometimes even I'll go ahead and download...

The omitted subject depends on the situation.

In many real conversations, leaving out 私 or 私たち sounds more natural than saying it explicitly.

資料 is a broad word. It often means:

• materials
• documents
• reference materials
• handouts
• data

In a meeting context, 資料 often refers to:

• meeting documents
• presentation materials
• handouts
• reference files

So 資料 is wider than just one English word. The exact translation depends on context.

It is a combination of:

• 公式 = official
• サイト = site, website

So:

• 公式サイト = official website

This is very common in modern Japanese: a native or Sino-Japanese word plus a loanword.

Also, サイト usually means a website in everyday usage when the context is online.

Yes. It ends with おきます, which is the ます form, so it is polite.

Polite version:

• 明日の会議の資料を公式サイトからダウンロードしておきます。

Casual version:

• 明日の会議の資料を公式サイトからダウンロードしておく。
• or in conversation: ダウンロードしとく
  This is a casual contraction of しておく.

So the original sentence is suitable for normal polite conversation or workplace use.

No. Normally it would be written without spaces:

明日の会議の資料を公式サイトからダウンロードしておきます。

The spaces here are just for learners, to make the parts easier to see.

That is very common in teaching materials, but not in standard Japanese writing.