A white window with "onshape account login" come in whenever I run some code prompting the importing of onshape assembly files like step and stp.

Basically whenver I to run these lines of code "exportedModel = smexportonshape(assemblyURL); smimport(exportedModel);" to import stuff from onshape an into simscape. A small white window will pull up and I cant do anything with it. Its just a blank white screen.

[DGM]

I don't have simscape or that particular tool (or an onshape account), so I can't test anything. That said, the login popup seems expected, though the fact that it's blank is possibly an issue specific to your OS. I don't know if anyone else is familiar with these tools, but it might be worth noting what OS you're using. If nobody on the forum knows, this sounds like something you might ask support about.

[Joseph]

yeah forgot to update this, it was my OS that was the problem i was using edge as my default once i switched to chrome it worked

[DGM]

If you want, you can answer your own question (and accept it). It might help the next person with the same problem, and having an answered question might make it more likely they'll read it.