This is generally due to the error in table creation which occurs because of the unicode which don't allow unique key in table for large characters.

You need to check if bp_cohort_info table is created in the database.

If not, then fire the below mentioned query in phpMyAdmin

CREATE TABLE IF NOT EXISTS wp1i_bp_cohort_info ( ID INT( 11 ) NOT NULL AUTO_INCREMENT,COHORT_NAME VARCHAR( 200 ) NOT NULL ,MDL_COHORT_ID INT( 20 ) ,PRODUCTS VARCHAR( 100 ) ,COURSES VARCHAR( 100 ) NOT NULL ,COHORT_MANAGER INT( 10 ) NOT NULL ,INCOMP_ORD VARCHAR( 50 ) DEFAULT NULL ,SYNC TINYINT( 4 ) NOT NULL DEFAULT '0',PRIMARY KEY ( ID ) );

Try purchasing the product again using Bulk Purchase plugin and let us know the results here: edwiser@wisdmlabs.com

This issue is caused due to lack of necessary permissions for the user mentioned in wp-config.php, you need to check if the user has permissions to create and edit the table in the database.