There's lots of competition and you probably won't find free virtual tour software or sites that do everything you won't.
Brodecki listed some of the challenge. One big one is knowing how to place arrows so when someone clicks an arrow they appear to move in that direction to the next pano.
Google lets people take a series of 360 photos and upload them to Street View as virtual tours. There are photographers that can do this or you can do it yourself. However, as Google notes, you'll need to use software or a service to connect your photos. Here's Google's info on that. https://www.google.com/streetview/contacts-tools/
The Unity Store has tools that let you do it all yourself. But those tools aren't free. One of them is over $200.
A less complex scenario might be where a 360 photo only has 3 arrows: show me the next photo, show me the previous photo, let me choose a photo.
Some sites let you navigate anywhere like you can do on Street View. And a site can also show you a filmstrip that lets you choose the photo you want to see.
A final solution might simply be to create a 360 photo slideshow that users can page through.
There are commercial sites that host your tour and help you build them but I don't know of a free one.
Note: Long ago Google did acquire a company that lets you build virtual tours with connected photos. But that only works/worked for web-based tours - not in VR. I can see if that still exists if that's an option. The tool automatically created those connecting arrows based on how you arranged your 360 photos. I'd have to look it up because it might not even be in my bookmarks anymore but I tested it and it worked well - for browser-based tours .. not VR tours.