syasin ga oosugite, daunroodo mo appuroodo mo zikan ga kakarimasita.

多すぎて means being too many or because there were too many.

It is built from:

• 多い = many / a lot
• すぎる = to exceed / too much
• て = connects to the next clause

So:

• 写真が多い = there are many photos
• 写真が多すぎる = there are too many photos
• 写真が多すぎて、... = because there were too many photos, ...

If you said 多くて, it would mean there were many, and... but it would not have the strong idea of too many.

In 写真が多い, the noun counted or described by 多い is commonly marked with が.

So:

• 写真が多い = there are many photos
• literally, photos are many

This is a very normal pattern in Japanese. A learner may expect 写真を somewhere, but 多い is an adjective, not an action done to the photos, so が makes sense here.

Here, て connects the first idea to the second idea and gives a reason/cause feeling.

So the sentence structure is basically:

• 写真が多すぎて = because there were too many photos
• ダウンロードもアップロードも時間がかかりました = both downloading and uploading took time

The て-form does not always mean cause, but in this sentence that is the most natural interpretation.

This is the pattern AもBも, which means both A and B.

So:

• ダウンロードも = downloading too
• アップロードも = uploading too
• together: both downloading and uploading

It emphasizes that the same thing is true for both items. Here, the same thing is that they both took time.

Here they are functioning as nouns that name actions.

Many Japanese loanwords like these can work as:

• nouns
• or verbal nouns with する

So you can have:

• ダウンロード = download / downloading
• ダウンロードする = to download

In this sentence, they appear as action-nouns followed by も:

• ダウンロードもアップロードも

That is why there is no する here.

Because 時間がかかる is a set expression meaning to take time.

Literally, it is closer to:

• time is required
• time is spent

So 時間 is marked with が.

Examples:

• 時間がかかる = it takes time
• お金がかかる = it costs money

This is a very common Japanese pattern, even though English uses take with a different structure.

かかりました is the polite past form of かかる.

In this sentence, かかる means:

• to take
• to require
• to need

So:

• 時間がかかる = to take time
• 時間がかかりました = took time / it took time

The past tense is used because the speaker is talking about something that already happened.

Because ダウンロード and アップロード are not the direct objects here. They are being presented as activities that took time.

The structure is not:

• something downloaded something

It is more like:

• as for downloading and uploading, both took time

If you wanted a fuller structure with verb-like wording, you could say:

• ダウンロードするのもアップロードするのも時間がかかりました。

That means almost the same thing, but it spells out the actions more explicitly.

Japanese nouns usually do not show singular/plural the way English does.

So 写真 can mean:

• photo
• photos

depending on context.

In this sentence, because of 多すぎて, the natural English meaning is photos, since too many photo would not make sense in English.

Yes.

For example:

• 写真が多すぎたので、ダウンロードもアップロードも時間がかかりました。
• 写真が多すぎたから、ダウンロードもアップロードも時間がかかりました。

These also mean that the first clause is the reason for the second clause.

The difference is mostly nuance:

• て = lighter, smooth, natural connection
• ので = more explicitly explanatory, often a bit softer/formal
• から = clearly causal, often a bit more direct

The original sentence with て sounds very natural.

The politeness comes from かかりました, which is the polite past form.

Compare:

• 時間がかかった = plain
• 時間がかかりました = polite

The rest of the sentence is neutral in style, and the final verb form sets the overall politeness level.

Yes. Japanese often leaves things compact, but you can make the structure more obvious.

For example:

• 写真が多すぎて、ダウンロードするのもアップロードするのも時間がかかりました。

This version makes it clearer that downloading and uploading are actions.

The original sentence is still perfectly natural. It is just a little more concise.