The default MacOS Areca driver doesn’t work on new M1 Mac, only for Intel-based machine. The macOS 11 had not been integrated any universal KEXTs into macOS, which means that users need to install universal KEXT to support Areca Thunderbolt devices on Apple Silicon. Areca universal drivers is no longer included in macOS Big Sur, which means you need to download the M1 universal driver from Areca website link and install Areca KEXTs manually.

Please follow the “Important notice for installing Areca driver for Apple M1 Mac in macOS Big Sur (11.0).pdf” document on website to install it.