Unable to save in OS drive and getting error

I finished installing windows 11 last night and updated drivers and everything without issue. BUT i am unable to save anything in the C drive where I installed the OS. I get this error " You don't have permission to save in this location. Contact the administrator to obtain permission." I only have one account on this PC.

I came across this video but I'm not sure if this is what my issue is. I'm not super tech savvy

https://www.youtube.com/watch?v=pzYAupkov3s