SQL Server 2022

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

DECLARE @T1_Customers TABLE 
(T1_Customer_id INT, 
 T1_FName VARCHAR(50), 
 T1_LName VARCHAR(50))
INSERT INTO @T1_Customers VALUES 
(1,'John','Darwin'),
(2,'Jane','Doe'),
(3,'Bobby','Black')

DECLARE @T2_Classes TABLE 
(T2_Class_id INT, 
 T2_Customer_id INT, 
 T2_ClassType_id INT, 
 T2_ClassName VARCHAR(50), 
 T2_Status VARCHAR(50))
INSERT INTO @T2_Classes VALUES 
(1,1,1,'Emergency Medical Dispatch v1','Pass'),
(2,1,2,'Emergency Medical Dispatch Instructor','Pass'),
(3,2,3,'Public Safety Telecommunicator','Pass'),
(4,2,1,'Emergency Medical Dispatch v1','Pass'),
(5,2,1,'Emergency Medical Dispatch v2','Fail')

DECLARE @T3_ClassTypes TABLE 
(T3_ClassType_id INT, 
 T3_ClassType VARCHAR(50))
INSERT INTO @T3_ClassTypes VALUES 
(1,'EMD'),
(2,'EMD-I'),
(3,'PST')

--SELECT * FROM @T1_Customers SELECT * FROM @T2_Classes SELECT * FROM @T3_ClassTypes

--FIRST ATTEMPT
SELECT * FROM @T1_Customers
  LEFT JOIN @T2_Classes 
    ON T2_Customer_id = T1_Customer_id 
      AND T2_Status != 'Fail'
  JOIN @T3_ClassTypes 
    ON T3_ClassType_id = T2_ClassType_id
      AND T3_ClassType != 'PST'

--SECOND ATTEMPT    
SELECT * FROM @T1_Customers
  LEFT JOIN @T2_Classes 
    ON T2_Customer_id = T1_Customer_id 
      AND T2_Status != 'Fail'
  LEFT JOIN @T3_ClassTypes 
    ON T3_ClassType_id = T2_ClassType_id
      AND T3_ClassType != 'PST'

SELECT * FROM @T1_Customers
  LEFT JOIN (select * from @T2_Classes
  inner JOIN @T3_ClassTypes 
    ON T3_ClassType_id = T2_ClassType_id
  where T2_Status != 'Fail' AND T3_ClassType != 'PST') tmp
    ON T2_Customer_id = T1_Customer_id ;

T1_Customer_id	T1_FName	T1_LName	T2_Class_id	T2_Customer_id	T2_ClassType_id	T2_ClassName	T2_Status	T3_ClassType_id	T3_ClassType
1	John	Darwin	1	1	1	Emergency Medical Dispatch v1	Pass	1	EMD
1	John	Darwin	2	1	2	Emergency Medical Dispatch Instructor	Pass	2	EMD-I
2	Jane	Doe	4	2	1	Emergency Medical Dispatch v1	Pass	1	EMD

T1_Customer_id	T1_FName	T1_LName	T2_Class_id	T2_Customer_id	T2_ClassType_id	T2_ClassName	T2_Status	T3_ClassType_id	T3_ClassType
1	John	Darwin	1	1	1	Emergency Medical Dispatch v1	Pass	1	EMD
1	John	Darwin	2	1	2	Emergency Medical Dispatch Instructor	Pass	2	EMD-I
2	Jane	Doe	3	2	3	Public Safety Telecommunicator	Pass	null	null
2	Jane	Doe	4	2	1	Emergency Medical Dispatch v1	Pass	1	EMD
3	Bobby	Black	null	null	null	null	null	null	null

T1_Customer_id	T1_FName	T1_LName	T2_Class_id	T2_Customer_id	T2_ClassType_id	T2_ClassName	T2_Status	T3_ClassType_id	T3_ClassType
1	John	Darwin	1	1	1	Emergency Medical Dispatch v1	Pass	1	EMD
1	John	Darwin	2	1	2	Emergency Medical Dispatch Instructor	Pass	2	EMD-I
2	Jane	Doe	4	2	1	Emergency Medical Dispatch v1	Pass	1	EMD
3	Bobby	Black	null	null	null	null	null	null	null