Ne želim ovakav plan.

In Croatian, ne is usually written separately from the verb in negative present-tense forms:

• želim = I want
• ne želim = I do not want

So Ne želim ovakav plan. is the normal way to say I don't want this kind of plan.

A few very common verbs have special negative forms, but želim is not one of them.

Želim is the 1st person singular present tense of the verb željeti (to want, to wish).

So:

• ja želim = I want
• ti želiš = you want
• on/ona želi = he/she wants

In the sentence, the subject ja is omitted because Croatian usually leaves out subject pronouns when the verb already makes the person clear.

Ovakav means like this, this kind of, or of this sort.

That is slightly different from ovaj, which usually just means this.

Compare:

• ovaj plan = this plan
• ovakav plan = a plan like this / this kind of plan

So Ne želim ovakav plan. does not just point to a specific plan. It also comments on its type or style.

Because ovakav has to agree with the noun it describes.

Here, plan is:

• masculine
• singular
• in the accusative as the direct object of želim

For masculine inanimate nouns, the accusative singular looks the same as the nominative singular, so we get:

• ovakav plan

Some other matching forms would be:

• ovakva knjiga = a book like this
• ovakvo pitanje = a question like this
• ovakvi planovi = plans like this

It is the object, but in this case the form happens to look the same.

The verb željeti takes a direct object in the accusative case.
However, plan is a masculine inanimate noun, and for many such nouns:

• nominative singular = plan
• accusative singular = plan

So the case changes grammatically, but there is no visible ending change here.

If the noun were feminine, you would often see the change more clearly, for example:

• Želim knjigu. = I want a book.

No. In this sentence, the object remains in the accusative:

• Želim ovakav plan.
• Ne želim ovakav plan.

Both use the same object form.

This is useful for English speakers because some other Slavic languages may change the object after negation, but standard Croatian normally does not do that in a sentence like this.

Yes, you could.

The difference is mainly in distance/reference:

• ovakav plan = a plan like this (closer to the speaker, more immediate)
• takav plan = a plan like that (a bit more distant, often referring to something already mentioned or associated with the listener)

So both are possible, but ovakav feels more like this sort of plan here / this kind I'm looking at now.

Yes. Croatian word order is fairly flexible, though the neutral order here is:

• Ne želim ovakav plan.

You can move things for emphasis, for example:

• Ovakav plan ne želim.
  Emphasizes this kind of plan.

• Plan ovakav ne želim.
  Possible, but less neutral and more stylistically marked.

For learners, the original sentence is the safest and most natural default.

Yes, because ovakav adds a judgment about the type of plan.

Compare:

• Ne želim plan. = I don't want a plan / the plan.
• Ne želim ovakav plan. = I don't want a plan like this.

The second one suggests that the problem is not necessarily the idea of a plan itself, but this particular kind of plan.

A simple English-friendly approximation:

• želim ≈ ZHEH-leem
• ovakav ≈ OH-vah-kahv

A few sound notes:

• ž sounds like the s in measure
• j sounds like English y
• v is a normal v
• Croatian pronunciation is generally quite regular, and each letter is usually pronounced clearly

So the whole sentence is approximately:

Neh ZHEH-leem OH-vah-kahv plahn.