A GNSS receiver isn't necessarily capable of receiving RTK corrections. For example, a standard off-the-shelf Garmin unit for recreational acitivities will generally only use SBAS (WAAS, EGNOS, etc.) for differential corrections and provide a one to a few meters of accuracy.
The higher-end GNSS receiver used for survey, construction, GIS and other applications that require high-accuracy results, have a GNSS board that offers RTK processing. This RTK correction will usually come from a local base station via a UHF or spread spectrum radio or internet-based corrections from a GNSS network.
Take a look at data sheets from some of the survey or GIS devices like the Leica GS18t, GS16, GG04 plus. These will outline RTK accuracy capabilities. These GNSS receivers contain the GNSS board as well as the GNSS antenna, so it is an complete solution. They are also multi-frequency, so obtaining high-accuracy results with longer baselines is easier compared to single frequency GNSS receivers.
From the looks of your device it is only the GNSS unit. You would need to have a GNSS antenna attached in order to receive signal. This antenna should be mounted in a way it has an good view to the sky for optimal reception.