To run the motor in open loop, the TMC6100 driver first needs to be configured to the TMC4671.
For this, the single line bit of the GCONF (0x00) register must be set to 0 (via SPI). One possibility is to use the SPI interface of the Landungsbrücke board.
Please note there's also special firmware for the BOB, in which the TMC6100 and TMC4671 are configured and can be set by the TMCL-IDE similar to other evaluation boards.