Help with duplicate title tags & Missing h1 on Weebly

I’m working on a website built with Weebly and using SEMrush to check its health. The top issues I’m running into are: Duplicate title tags Duplicate content Missing H1 tags Incorrect pages found in sitemap.xml My client isn’t open to switching to another platform due to budget constraints, so I have to make it work within Weebly. I’ve also read a lot of negative experiences with Weebly since it transitioned to Square, which makes this even more frustrating. If anyone has experience dealing with these SEO issues on Weebly, I’d really appreciate your advice. Also, how do I make sure the sitemap.xml is correct in Weebly?