Updates to the _hdf_maxwell_error message and download links #1320

Job	Run time
call-iotests / Test on (ubuntu-latest) (3.9) (1.26)	8m 42s
call-iotests / Test on (ubuntu-latest) (3.9) (2.0)	8m 57s
call-iotests / Test on (ubuntu-latest) (3.12) (1.26)	8m 57s
call-iotests / Test on (ubuntu-latest) (3.12) (2.0)	8m 23s
	34m 59s

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