Is the new version release compatible with joomla 1.5?

No, it's not. We are no longer developing new features for Joomla 1.5. The Joomla 1.5 compatible releases are still available and we do provide support if any issues are found and will fix them. However, we're not implementing any new features for Joomla 1.5 at this time. It's simply too time consuming to support that old of a version of Joomla and there are too few users still on it to fund that development.

I hope that helps explain,
Alex

The message I left above should answer your question about Joomla 1.5 compatibility. The newest release is not available for Joomla 1.5 and won't be. We still do have the v1.2 release available for download for our subscribers which works on Joomla 1.5. We fully support that release, but will not be adding new features.

Also can we customize its button, styles etc as per our requirement ?

I don't know what your requirements are. There are ways to customize the looks of the Login with LinkedIn button and we can help you do that.

Thanks,
Alex

We don't have separate subscriptions for each Joomla version. If you subscribe to JLinked, you'll have access to the last Joomla 1.5 release as well as the newer Joomla 2.5 and 3.x releases. You can read the final blog post for JLinked v1.3, which is the one available for Joomla 1.5, below:
www.sourcecoast.com/blog/extensions/impr...istration-for-joomla

To subscribe, please use the following link:
www.sourcecoast.com/index.php?option=com...g=jlinked&view=level

Thanks,
Alex