Once you have your text in place in the template, you can try compiling it. If you are using TeXShop on a Mac, you will need to do three compilations, two times each (you should just get into the habit of hitting "Typeset" twice).
First, typseset it normally (twice), with the compiler set to LaTeX. Look at the log and make sure the only errors or warnings are "Citation unknown" or "reference unknown". This message is because you haven't connected the file to the BibTeX database yet, and it doesn't know to what the citations are referring. You should, however, make sure there are no other errors or warnings.
Once you have reduced the errors to only the citation errors, switch the compiler to BibTeX and typeset twice (you should be compiling your primary document, not the database itself). Look at the log output and make sure there are no errors or warnings. The most common error is that a format is incorrect. You probably have a bracket, a comma, or a quotation mark in the wrong place. The most common warning is that some information it expects to find, like a title or a publication date, is missing. Make sure you have filled in all the relevant information in your database.
Once you have run BibTeX twice, switch back to LaTeX and compile twice again. Now it should give you no citation errors or warnings, and when you look at the PDF file, you should have a very nice set of references at the end of your proposal that all match up to citations in the body of your proposal.
If you are using Overleaf, it does all this automatically.
YouTube has lots of resources about writing proposals. Here are a few. Can you find better ones?