Bitnami does not offer a distinction between payment or free plans, all our applications are free on the Bitnami side, you will only be charged if you use a cloud provider; in this case, you will pay the instance depending on the size, use, disk, etc. as established by the cloud provider, in any case, this charge is not related to Bitnami.
So, if you are using the Windows installer, VMs, container or any other flavor not have any expenses.
Related to TestLink specifically if the application has different plans you should contact the TestLink team for more information.
I just installed Testlink and I am able to see the different options:
Carlos R. Hernández