The API keys are for individual use and are linked to your institution/organisation credentials. DO NOT SHARE THEM.
In the context of a literature review, which needs a low request rate and quota, you do not need a key to use the PubMed API.
More info at: https://pmc.ncbi.nlm.nih.gov/tools/developers/
Well done!
Now that you got your API keys, you can continue to the next tutorial → LitFetchR (Tutorial)