mount the partition to some subdirectory of /home/<username>, or even split it and mount its parts to /home/<username>/Downloads, /home/<username>/Movies etc
it's more of a hint that if I'm trying to create something inside those directories then I'm doing something wrong (like forgetting to mount a filesystem) and "permission denied" errors let me know that I am.
Now I understand.
This is all new to me bro.
Even I don't know if I will go this further to explain something to someone.
Thank you for the suggestion.