limesurvey - within a wordpress with : Unstable Release 4.3.27

[dil_bert]

hi there good day 

today i have a special question: - fresh install of limesurvey - within a wordpress with : Unstable Release 4.3.27 (from 17.11.2020)

see the following things: 
on a wordpress - see the structure: 

https://www.mypage.de
wordpress-files: 3750 

and here the limesurvey - files are stored.
https://www.mypage.de/umfrage/

permisson of the umfrage folder: 
limesurvey-files: 750 

well - i get back when i try to acess the admin-page: 
https://www.mypage.de/umfrage/admin

i will get this page: https://www.mypage.de/umfrage/index.php?r=admin

Internal Server Error
Application runtime path "/sites/www.mypage.de/umfrage/tmp/runtime" is not valid. Please make sure it is a directory writable by the Web server process.
An internal error occurred while the Web server was processing your request. Please contact the webmaster to report this problem.
Thank you.

well i do not know if the permission are enough!? 
do i need to have some kind of htaccess or something alike

love to hear from you