Hey @Gideon So, thanks for your answer
Well I thought that's what I had done in the first place, but I did it again following more precisely what you described and it produces the same result : 404 not found on the the domain-name/processwire admin, and 404 on the form (embed). I downloaded the processwire-master folder entirely, then deleted it from the public_html webroot, then reuploaded only the contents it (site, wire, etc). I also tried just moving the processwire-master to the ...I guess server root ? (1 folder up from public_html) then moved everything inside back to public_html. Same result in all cases. Did I misunderstand your directions ?