Language files not installed in 6.4.0-RC1

[Pinkeltje]

Describe the bug
Installing language files (pkg_kunena_languages_v6.4.0-RC1_2024-12-22.zip) fails

To Reproduce
Install K 6.4.0 RC1
Install language files

Expected behavior
Language files installed.

Actual result
Warning
Files Install: Failed to find source folder: [ROOT]\tmp\install_676d3cb5639cc\language\install_676d3cb570cd3/admin
Files Install: Failed to find source folder: [ROOT]\tmp\install_676d3cb5639cc\language\install_676d3cb592f80/admin

Screenshots
If applicable, add screenshots to help explain your problem.

System information (please complete the following information)

Joomla version: 5.2.2
Kunena version: 6.4.0 RC1
Php version: 8.2.12
Database version: 10.4.32-MariaDB

Additional context
When extracting i.e. com_kunena_nl-NL_v6.4.0-RC1.zip it only contains com_kunena_nl-NL.xml and no language files.