Open Photoshop and go up to your menu bar and click on Wiindow:
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This will open a menu of choices and click on Libraries - this will open the Library tab where you'll find the Martin Palm brushes:
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Double click on that group and it will open the group to show all the brushes (this is the grid view)
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Now got to your tools menu and activate your brush by clicking on it:
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Now go back to your grid view of brushes and click on any brush - that will load it so you can use it:
Here I've clicked on the grass brush and added it to my eggs...
Took me a bit to discover how to do it - generally I just download a brush and load it into PS. Haven't used my CC Libraries before but lots of stuff there!
Let us know if this works for you.