@cantstartagain I'm so sorry that this job hasn't turned out to be what you expected, especially after it sounds like you had a bad time in your previous job, too. It sounds to me like you're very angry about that and I don't blame you - it should be up to your manager to help you make this work.
I think how you respond to your current situation depends on whether your gut is telling you this is workable with some adjustments, or whether you'd be better to cut your losses and look elsewhere
I've worked in partly and fully remote teams, and it's always a bit of an adjustment. The advice I would give you is to start to get to know your teammates a bit - you've only been there 6 weeks so it would be perfectly reasonable to schedule 1-1 getting to know you calls to understand their roles and start to see how yours might evolve. And then, once you've established contact, keep it up, using Slack or Teams or whatever tech your team use. I am in touch with very few people from the corporate (Big 4) job I left after 20 years, just before the pandemic, but two of them are and always have been based in other countries, so our friendship was built online.
I'd also say talk to your manager - not necessarily a big heart-to-heart but a call at least once a week, to keep up to date with what the team is doing and how you can fit in. And make sure she knows that you need her to task you in the early stages as you learn the job.
The best-run remote teams I've worked in have had regular get-togethers - maybe only once or twice a year, but as you already know, some face-to-face contact is really badly needed - we're social animals. Are the rest of the team in just a couple of places, or are they also scattered? Is there a natural cycle of events which could be a frame for you all to meet - industry conference, board meeting where you support/report to one of the board members, that sort of thing?
You have had some good advice (or advice that I'd regard as good!) on here, but it seems to me that you're not currently in a frame of mind where you can use it. I second what several PPs have said about establishing routines of going into the office - yes, some people change the days they're in, but there will be others who regularly do the same couple of days, and unless the office is 100% staffed by sociopaths, there will be plenty who'd be happy to go for a coffee or lunch with a new joiner and talk to them. Work friendships don't have to be deep to provide you with company and structure. Good luck to you. I hope you can make it work for you.