There is more than one way for a credential to end up in a wallet, and OID4VCI describes them in its Use Cases appendix. They differ in who starts, how the wallet learns what is on offer, and which grant does the authorizing — so pick one and the rest of the workflow follows it, and change it whenever you like.
The page on the issuer's own website where a person asks for a credential — a university's "get your diploma" page, say. The offer use cases below send you there. OpenID4VCI does not say what such a page is called, so this is a whole URL. Against an issuer with no such page, paste its Credential Offer into step 1 instead.