Zotero 7 (the latest main version) broke compatibility with Zotfile, but there are plugins around that are either forks of the version that ran on Zotero 6 or reimplementations of Zotfile’s features.
I personally have been using Zotero Attanger and it’s been working great for me.
I’ve had a Kindle Paperwhite in the past and now I have a Kobo Clara 2E (that’s the BW one).
I prefer the Clara because:
They both have water resistance and warm light. The Paperwhite’s screen is a bit bigger, but the difference is not monumental.
In the end, they are similar enough both in terms of specs and price that depending on your use case you will be fine with either one, but if anything I mentioned above is an important factor to you then I hope this was helpful :)