The UK left the EU on 31 January 2020 and entered a transition period, which ended on 31 December 2020.
If you were not living in the UK by 31 December 2020, unfortunately, you will not be able to study at UGM Manchester at this time. If you were living in the UK before the end of the transition period, you may continue to reside, study and work in the UK under the EU Settlement Scheme.
You can read more about eligibility for British citizenship and the EU Settlement Scheme on the UK Government website: https://www.gov.uk/british-citizenship.