Error during command authentication.

I'm a recent Brown alumna and I had a question about starting a small lending library for a church group with which I'm affiliated. Brown's librarians have been so helpful to me in the past, so I figured I'd give it a shot asking you all about this! 

We're hoping to have an online database where we can catalog books (and add specific tags based on the subject), record ISBN numbers, and show which books are checked in, checked out, or on hold, etc. We're looking for something that would require little in-person maintenance, as there would be no hired staff specifically for the library. But we would want to be able to know who has which book, have due dates, etc. It would be great if the interface had a way to scan ISBNs or barcodes to ease inputting new books into the system. Our collection of books totals 300, give or take, so it's not a huge collection by any means. It would also be a great bonus if there were a way to have an online notes section for each book that we could edit.

I was wondering if you had any advice about which websites/databases are good for this project. I've been looking at Libib and TinyCat (the latter is an offshoot of LibraryThing). TinyCat looks pretty promising but I wanted to get your opinion if you have one regarding that site or any other sites you prefer for these purposes. We have a small budget, so the cheaper the better as long as it's functional, secure, remotely accessible (besides actually coming into the place to retrieve and return the books), and not too clunky.