With the release of MATLAB R2021a, the daqmlconverter.dll and daqasyncio.dll files are no longer included. If a user attempts to run an example that uses a Data Translation data acquisition device, with MATLAB R2021a, then MATLAB will report a 'file not found' error.
In order to resolve this error, exit MATLAB and download the attached 'Files_for_MATLAB_R2021a.zip' file to the target system with MATLAB R2021a. Extract the two files (daqmlconverter.dll and daqasyncio.dll) from the zip file to the 'C:\Program Files\MATLAB\R2021a\toolbox\daq\daqsdk\bin\win64' directory. Afterwards, open MATLAB again and continue to use your example file with the Data Translation device.