Can you submit to Arxiv without an institutional affiliation?
I've had no affiliation while submitting to the arxiv regularly before.  I just use "N/A" in that field of my profile.  Never had a problem.

Others have asked very similar questions before. These all seem to be about people having previously posted with an affiliation to now losing or changing their affiliation, rather than someone who has never posted. The former would be my own situation. Still, the key to entry is getting endorsed.  Once you're in, you are permanently in, short of administrative actions for violations. These could happen if, say, you falsely report your affiliation.  But simply not having an affiliation is not an issue.