REDEEMABLE EQUITY - Narrative (Details) - USD ($)	3 Months Ended	9 Months Ended
	Feb. 28, 2022	Feb. 28, 2022	Nov. 30, 2021	May 31, 2021	Feb. 28, 2021	Nov. 30, 2020	May 31, 2020
Temporary Equity [Line Items]
Accrued Dividends	$ 1,242,000	$ 1,242,000
Series C Convertible Redeemable Preferred Stock
Temporary Equity [Line Items]
Temporary equity outstanding (in shares)	676,086	676,086	660,000	660,000	0	0	0
Redemption notice period		30 days
Temporary equity issued (in shares)	676,086	676,086		660,000
Conversion price (in dollars per share)	$ 0.13	$ 0.13
Accrued Dividends	$ 402,150	$ 402,150
Series C Convertible Redeemable Preferred Stock | Dividend rate, option one
Temporary Equity [Line Items]
Paid-in-kind dividend rate	10.00%	10.00%
Series C Convertible Redeemable Preferred Stock | Dividend rate, option two
Temporary Equity [Line Items]
Paid-in-kind dividend rate	12.00%	12.00%
Series C Convertible Redeemable Preferred Stock | Dividend rate, option three
Temporary Equity [Line Items]
Paid-in-kind dividend rate	15.00%	15.00%
Series D Convertible Redeemable Preferred Stock
Temporary Equity [Line Items]
Temporary equity outstanding (in shares)	1,413,624	1,413,624	1,380,000	0	0	0	0
Redemption notice period		30 days
Temporary equity issued (in shares)	1,413,624	1,413,624		0
Accrued Dividends	$ 840,300	$ 840,300
Series D Convertible Redeemable Preferred Stock | Conversion, option one
Temporary Equity [Line Items]
Conversion price (in dollars per share)	$ 0.44	$ 0.44
Series D Convertible Redeemable Preferred Stock | Conversion, option two
Temporary Equity [Line Items]
Conversion price, percent of share price	75.00%	75.00%
Series D Convertible Redeemable Preferred Stock | Conversion, option three
Temporary Equity [Line Items]
Conversion price, percent of share price	75.00%	75.00%
Series D Convertible Redeemable Preferred Stock | Conversion, option four
Temporary Equity [Line Items]
Conversion price, percent of share price	75.00%	75.00%
Series D Convertible Redeemable Preferred Stock | Dividend rate, option one
Temporary Equity [Line Items]
Paid-in-kind dividend rate	10.00%	10.00%
Series D Convertible Redeemable Preferred Stock | Dividend rate, option two
Temporary Equity [Line Items]
Paid-in-kind dividend rate	12.00%	12.00%
Series D Convertible Redeemable Preferred Stock | Dividend rate, option three
Temporary Equity [Line Items]
Paid-in-kind dividend rate	15.00%	15.00%