In documentation article Requirements versions 2.0.1 to 2.11 for TimescaleDB are listed as supported. Version 2.0.1 of TimescaleDB does not support PostgreSQL 13.0, which is another requirement for Zabbix. More info on supported PSQL versions here.

Additionally, when trying to build Timescale 2.0.1 on a machine with PostgreSQL 13 you get this error:

-- Compiling against PostgreSQL version 13.12
CMake Error at CMakeLists.txt:244 (message):
  TimescaleDB only supports PostgreSQL 11 and 12


-- Configuring incomplete, errors occurred!

Support for PostgreSQL 13 was added on TimescaleDB version 2.1.0 - release notes here. The oldest supported TimescaleDB version should be changed to 2.1.0.

Note: this also means changes in Server and Frontend checks. Server checks DB version when starting. Frontend shows a warning in Administration -> Housekeeping when the version is not supported.