Back in AD&D, a spell scroll was created by basically casting a spell onto a specially prepared scroll. The next person to read said scroll was able to cast the spell exactly as the original creator.
I don't think that's how it works in 5e. In fact, I thought I'd read somewhere that only a member of a spell casting class that's able to use the spell inscribed on a spell scroll is able to use that scroll. But I can't for the life of me find where this is written!!
So, who is able to cast a spell from a spell scroll?