You are smothering your shrub.  It has not been in the ground long so dig it up (carefully) and check the roots.  They should be white and firm.  Cut off any that are mushy and/or brown and rotting.  Remove the tarp.  Dig the planting hole again.  If your soil is heavy or has a lot of clay, mix in some compost and loosen the sides of the hole to allow for drainage.  Replant with the highest roots just barely below the surface of the soil.  Tamp down the soil lightly to firm it up.   You can put some organic mulch like shredded bark around the base but pull it back several inches.  To check when to water, stick your index finger into the soil up to the second knuckle.  If the soil is still dry at the tip of your finger, water deeply and slowly.  Allow the soil to dry out on top again and then recheck.  You will soon be able to judge when and how much to water.