Warning: mysqli::mysqli() [mysqli.mysqli]:

For instance the sub-class that stores token data in a MySQL database uses the mysqli extension, not the the old mysql extension that was deprecated in PHP 5.5 and will not be available in PHP 7. So this class will continue to work in PHP 7.

I won't know if there is a missunderstanding, it is
simply not usable.

Sorry, maybe I am having difficulty to understand your point because I did not understand your explanation why it is unusable for you.

Anyway, that is OK. My goal here is to understand if you have difficulties to help you using the package.

It is hard to find OAuth packages that support all the features of the protocol because it is complex and some features are hard to implement.

This class supports many of those hard features like automatic refresh of tokens that expire, send API calls offline even when the user is not present, and provides built-in configuration for many of the most popular APIs.

That is why more than 16,000 users are using this package.

You may read more about these advanced topics in the package blog:

phpclasses.org/blog/package/7700/

If you try other packages and find any difficulties, you are always welcome to try this package again to check if it is easier for you.

I didn't say your class is not good, and that it
will be used by 16000 People speaks at its own.
I don't like to show all my code but if you will
see it will have some Errors.
The implementation of your OAuth API is not possible
as it have some Errors and I have to modify to many
files and classes.
I guess you will do that in one week or less time
but you don't have the time for it.
Our Servers have only php 5.4 and above, it doesn't make
sense to use a php 4 class. I have seen some Hostings in
middle America offer php 4 Hostings.
You could see with the bitexpert Composer classes they
use allways php 5.6. they are up to date.

Can you give an example of one error you see so I can understand what you mean?

Anyway, as I mentioned before this class does not work in PHP 4. The bare minimum is PHP 5.2 but there should be no reason why it should not work on later versions. I use it in PHP 5.4 all the time.