os calendar not working

hi there
I just bought and paid the os calendar extension. unfortunately it does not work!
our settings are:
- Joomla 6
- Template JA EGO from Joomlart
- PHP 8.3.25
- MySQL (PDO) 8.0.26-16

If I point in the component to any item - it will result in the error message:
Failed opening required '/var/www/vhosts/h754652.web208.dogado.net/ferien-in-fuessen.de/components/com_osproperty/helpers/common.php' (include_path='.:/opt/plesk/php/8.3/share/pear')

can you pleas help me with the issue?
Thank you very much in advance

PS:: I bought nit because there is stated compability with joomla 6
see screenshot
 

Hi,
OS Calendar is an add-on for OS Property and cannot work independently.
Currently, we are also working on improving OS Calendar so that it can run well on Joomla 6, along with adding some new features needed for booking systems.
If you want to use OS Calendar, I recommend purchasing OS Property as well. However, if you do not wish to buy OS Property, we can offer you a refund for your OS Calendar purchase.
Please let me know how you would like to proceed or if you have any other questions.
Thanks
Dam

hi Dam
thank you very much for your fast reply.
I just recently bought as well the os services booking but I realized that it is to complicated for me.
Actually I can not use it! Can I just swap the extension instead of buy a new one.

Means: Can I give back the os services booking and get the os property instead? that would help a lot...
Thank you very much in advance
franziska