I am a heavy audiobook user with several accounts based around the country (family let me use their log ins as they don't use them). I was also able to join the library of my 2 neighbouring areas without being a resident or paying council tax there. One I had to pop in for a card, the other posted it to me. They each game me an immediate temporary digital account until my full card was sorted.
Depending on the service your library offers, you are likely to get an allowance of 6 or 10 each for ebooks and audiobooks. This can be used for a loan or a hold. The loan period is usually either 2 or 3 weeks. The best way to use them is to keep a few back for instant loans and use the rest for holds for books you really want. Even if the book is showing as unavailable until February, it's still worth using a hold as many users will return it early, or remove the hold which will bump up your place in the queue and reduce the time you are waiting. I got the full Booker Longlist before the Shortlist was announced via the library. Some libraries are better than others. The worst one I know of has only 3k audiobooks in the catalogue, with the better ones offering 13-16k. You can always find something you want to listen to while you wait for something else. You get an email when your holds are ready.
Borrowbox seems to be the more popular app. Overdrive is sadly being phased out for Libby, which I'm not a huge fan of.
For libraries with Borrowbox, there is always a website as well as an app which is usually
Town.borrowbox.com or
Borrowbox.com/town
You library or council website should direct you to the right place.
In the library I work in, footfall and item lending data is very carefully monitored as we get more funding if the service is used and we can prove it. Same goes for digital use. Each library in the area has a different demographic, the ones with higher book loan data get more new books delivered, those with higher computer use get bigger computer suites. Our Borrowbox just got more items as they moved to the next package up when usage increased. It's very much a 'use it or lose it' service. Your libraries desperately need you to visit and to borrow items, even digitally. I know some libraries will have opening times that make it impossible to visit if you work full time, so it's not always simple, but if you can, please do use them. Max your loans people, make us look busy! And if they have a digital door counter, waft past it several times. 