I cant install any extension 😞

Im having problems to install extensions, also have noticed my version doesnt have an extension window at the top of the scree

Saying I can’t install any extension without giving any further information is like saying I can’t eat a banana. I would have to ask, have you forgotten to peel it, are your trying to eat it sideways all in one go?

So please, what issues are you having?
Are you attempting to install directly from the warehouse within SU or are you getting them somewhere else and attempting to make them install by clicking on them?

Many extensions are available as .rbz and can be installed using the Install extension option within the Extension Manage. Many can be downloaded directly from the EWarehouse from within SU?

Sometimes people have issue connecting to the Ewarehouse, other times they are trying to install incorrectly and other times the issues are very different.

So we need to know what extension, where from and how you are trying to install.

PS there won’t be an extension menu until there is an extension installed to use it.

You only see the Extensions menu after you have installed an extension that needs that menu. Open Window/Extension Warehouse, make sure to sign in with the email address you have used to download extensions in the past, and then click on your avatar. From that, choose My Downloads.

I looked at your list of extensions, and aside from one trial, your other ones were free extensions, and so they may not be in your downloads list. Search for each one that you want to add to SketchUp 2020, and then install them. After that they should appear in your My Downloads list.