DE10-Standard UART; Problem with pins

[Szymmad]

Hello,

I have a DE10-Standard board and I am trying to create a simple design to learn how to use UART. I am doing excaclly the same steps as in this tutorial from Intel: https://www.youtube.com/watch?v=7xJ9dhVDCwU&fbclid=IwAR3NDEoC2kW88870pbqcrzSfmlRyCtmMfaOLXgmKI9JlTrpcsyGztJj0vW0
Of course, when it comes to pin assignment I use pins for my board. When I get to step 2-1, I compile the design but I get an error:

Error (14566): The Fitter cannot place 2 periphery component(s) due to conflicts with existing constraints (2 pin(s)). Fix the errors described in the submessages, and then rerun the Fitter. The Intel FPGA Knowledge Database may also contain articles with information on how to resolve this periphery placement failure. Review the errors and then visit the Knowledge Database at https://www.altera.com/support/support-resources/knowledge-base/search.html and search for this specific error message number.
Error (175020): The Fitter cannot place logic pin that is part of ur ur in region (79, 81) to (79, 81), to which it is constrained, because there are no valid locations in the region for logic of this type.
Info (14596): Information about the failing component(s):
Info (175028): The pin name(s): serial_txd
Error (16234): No legal location could be found out of 1 considered location(s). Reasons why each location could not be used are summarized below:
Error (184016): There were not enough single-ended output pin locations available (1 location affected)
Info (175029): C25
Info (175015): The I/O pad serial_txd is constrained to the location PIN_C25 due to: User Location Constraints (PIN_C25)
Info (14709): The constrained I/O pad is contained within this pin
Error (175020): The Fitter cannot place logic pin that is part of ur ur in region (79, 81) to (79, 81), to which it is constrained, because there are no valid locations in the region for logic of this type.
Info (14596): Information about the failing component(s):
Info (175028): The pin name(s): serial_rxd
Error (16234): No legal location could be found out of 1 considered location(s). Reasons why each location could not be used are summarized below:
Error (184016): There were not enough single-ended input pin locations available (1 location affected)
Info (175029): B25
Info (175015): The I/O pad serial_rxd is constrained to the location PIN_B25 due to: User Location Constraints (PIN_B25)
Info (14709): The constrained I/O pad is contained within this pin

Thank you for your response.

[JonWay_C_Intel]

Could it be due to this: https://www.intel.com/content/www/us/en/programmable/support/support-resources/knowledge-base/solutions/rd01292013_881.html