The project is open source, what you're complaining about is that the LDAP feature isn't free. You have to try to understand that they can't pour in thousands of hours across a development team without making money. How are their developers gonna get paid?
The golden nugget with these kind of projects, from these kind open source-minded companies, is that being a paying customer contributes greatly to a better and healthier product with regular feature additions. Compared to the more frequently found companies that is closed source, commerical-only and only provide bugfixes I think that it is perfectly fine that the LDAP-feature is behind a paywall.
Let's not fool ourselves, there is no such thing in these companies and products that appeared during the last few years. There is no free/open-source spirit, it's open-washing and the model usually get more closed and more closed year after year (going through an incredible variety of licenses, market segmentation and other marketing & sales tricks), following the evolution of the owners' greed.
It's a regular business that is freemium-minded, period.
The golden nugget with these kind of projects, from these kind open source-minded companies, is that being a paying customer contributes greatly to a better and healthier product with regular feature additions. Compared to the more frequently found companies that is closed source, commerical-only and only provide bugfixes I think that it is perfectly fine that the LDAP-feature is behind a paywall.