From the log:
2024-11-25 21:33:54,950: DEBUG - FreshRSS failed requirements:
2024-11-25 21:33:54,950: DEBUG - • curl
2024-11-25 21:33:54,950: DEBUG - • pdo-mysql
2024-11-25 21:33:54,950: DEBUG - • mbstring
This seems to be the same problem as in this forum thread.