As long as you are certain that it is 125kHz, the xEM will be able to be written.
One clause, door looks can be notoriously difficult to open with an xSeries such as an xEM, but not always.
There can also be some mods / add ons that may stack the odds in your favour if required.
As equipter’s link above, plus there are a couple of install guides to follow here on the forum
Are you going to use
Windows, linux, Mac or Android?