Au DDR tutorial gives "Critical Warning" on build

I was duplicating the tutorial on how to use the DDR memory on the Au, but I get a Critical Warning upon building.
The design runs ok, but the “Critical” part of the warning worries me a bit.

I think the problems start right at the start when I add the Memory Controller. It complains about not finding an .xci file:

Compare this to exactly the same stage in the tutorial:

It makes the same complaint after I add the clock wizard core (in fact it seems to say this after generating any cores).
When I add in all the code (exactly duplicating the tutorial), it successfully builds, but gives me the critical warning:

Parsing XDC File [C:/NarwhalDevices/FPGA_projects/DDR_example/work/constraint/alchitry.xdc] CRITICAL WARNING: [Constraints 18-1056] Clock 'clk_0' completely overrides clock 'clk'.

Should I just ignore the warning, or is it a sign that there is something wrong, and it will come back to bite me?


Note: I’m using Windows 10, Alchitry Labs 1.2.1, and Vivado 2020.1
(see attachment for full output)

this warning: [size=small][font=Monaco, Consolas, Courier, monospace]CRITICAL WARNING: [Constraints 18-1056] Clock ‘clk_0’ completely overrides clock ‘clk’. is caused by twice definition of clock. First is in aulchitry.acf, second is part of Clock generated by wizard. Don’t care about, it is not critical. Or you can run your project in Vivado and remove first clock creation in alchitry.xdc file to avoid this critical warning.