You will receive the antigen test results at the sampling point, a short while after the sampling.
The PCR laboratory test results are usually available within 48 hours of a receipt of the sample by the laboratory. The laboratory sends you the test results automatically by a text message or personally. More at I have received a SMS stating a positive test result.
You can download the certificate with the test result at ocko.uzis.cz or with the help of the validation app Tečka.
More at Certificates.