This macroalgae will attach itself within 2-3 days when it gets good light to rock etc but a drop of superglue will help to keep it in place of course faster :)
When you like to get it natural attached we recommend to leave it for this time on a small piece of rock or similar in an area without a current.  If you don't have such an area in your aquarium use some rubber band or place in-between some rockwork to hold it in place until it has attached itself.  We don not recommend just to place the Ochtodes macroalgae on the substrate, as it needs something to attach itself to stay in place.
We hope this helps.
Kind regards  Livealgae UK